1. Field of the Invention
This invention relates generally to sound devices that are used to disperse or deter animals and, more particularly, to an electromechanical horn device that produces a very loud audible sound in a frequency range in the region of greatest hearing sensitivity of a particular animal species, such as canines, and at a decibel level and pattern specially calculated to effectively disperse or deter an aggressive animal in a non-detrimental manner.
2. Background Art
In the following discussion, for purposes of understanding, the following terms related to sound are given the ordinary and customary meanings attributed to them by those of ordinary skill in the art. “Frequency” refers to the “pitch” of a sound measured in Hertz (Hz) or Kilohertz (kHz). A Hertz is a unit of frequency equal to one cycle per second. Higher frequency=higher pitched sound. “Hearing range” describes the range of frequencies that can be heard by an animal or human, though it can also refer to the range of levels.
Another important aspect of sound is the loudness or intensity of the sound. “Sound Pressure Level” (SPL) correlates to the “loudness” of sound measured in decibels (dB). A “decibel” (dB) is a unit used to measure the sound energy relative to a reference level. An increase of ten decibels in the power of a signal is equivalent to increasing its power by a factor of ten, and the perceived loudness by a factor of two (doubling perceived loudness). Zero decibels is defined as the average human threshold of hearing at 1 kHz. Generally speaking, higher sound pressure correlates with louder sound. The more distant the receiver of the sound is from the sound source, the lower the perceived sound level, thus, sound pressure level (SPL) specifications are typically expressed with regard to the distance (usually in meters) from the sound source and how loud the sound pressure level should be at that distance. Some breeds of dogs respond to a much lower intensity of sound than the average human. Dogs can also hear a broader range of frequencies, some at lower decibel levels than humans.
A pitched sound consists of a number of frequency components arranged in integer multiples of the “fundamental” frequency. These components are called harmonics and are numbered according to the corresponding integer multiple. Thus, the fundamental is the first harmonic. The second harmonic has twice the frequency and the third harmonic three times the frequency of the fundamental, and so on.
The term “audible sound”, as used herein, refers to sound which can be perceived by the human ear. In humans the audible frequency range is about 20 Hz to 20,000 Hz (20 kHz), with the frequency range of 3 kHz to 4 kHz (3,000 Hz to 4,000 Hz) being the most sensitive range.
In dogs the “audible” frequency range which can be perceived is about 40 Hz to 60,000 Hz (60 kHz), which is a much greater range than that of humans, with the frequency range of about 4 kHz to 10 kHz (4,000 Hz to 10,000 Hz) being the most sensitive range (i.e. the frequencies that can be detected at the lowest intensities), depending upon the breed and age. Studies by audiology researchers suggest that dogs hear little above 30 kHz (30,000 Hz).
The term “ultrasonic” sound, as used herein, refers to anything above the frequencies of audible sound, and nominally includes anything over 20 kHz (20,000 Hz). Most “silent” dog whistles and bark controllers produce “ultrasonic” sounds at frequencies higher than those audible to humans.
Situations often occur wherein individuals, or groups of individuals, may find themselves confronted by at least one dog. These situations tend to necessitate fleeing from the animal, scaring the animal off, or some other defense tactic. Unfortunately, the individual or individuals may become hurt in attempting to flee or discourage the animal. The animal may charge or attack the individuals and/or chase them causing further stress to the individuals and increasing the chances for injuries to both the individuals and the animals.
There are several commercially available dog deterrent devices such as the DAZER™ and DAZER II™, manufactured by Dazer International, Peterborough, England and distributed by K-II Enterprises of Syracuse, N.Y., emit high frequency “ultrasonic” sound bursts of 25 kHz (25,000 Hz) at a decibel level of 115 dB (SPL) at 0.5 meter reference. The DAZER devices are advertised as having an effective range of about 15 feet and increasing effectiveness as the dog becomes closer to the sound source.
Most “ultrasonic” dog deterrent devices provide high frequency “ultrasonic” sound burst to produce a startle effect to interrupt a dog's barking or the dog's aggressive behaviour, and their deterrent effectiveness depends upon the dog's reaction to the strange sound. However, such devices are not effective on all dogs. For example, the dog's reaction depends upon its age, breed, mental state, temperament, health and intelligence. For instance, smaller dogs react better to “ultrasonic” noise, whereas medium to large sized dogs are more responsive to “audible” blasts of sound.
A typical “ultrasonic” sound burst produced by most ultrasonic dog deterrent devices is in the frequency range starting at about 20 kHz (20,000 Hz), which is above the most sensitive region of a dog's hearing (between 4 kHz and 10 kHz), but is at a decibel level to be detected by some dog breeds at close range and produce the startle effect. Another problem with “ultrasonic” dog deterrent devices is that the ultrasonic frequency does not disperse well and becomes more directional as the frequency increases, thus, their effectiveness can also depend upon how precisely the user aims the sound emitting device.
The more distant a receiver of the sound (the dog) is from the sound source, the lower the perceived sound level (dB). For example, the perceived sound level (dB) of an “ultrasonic” deterrent device which has a decibel level of 115 dB (SPL) at 0.5 meters (approximately equal to 1 foot 7½ inches) would be much less at a distance of about 15 feet. Moreover, the sound pressure level (dB) is only one component of the sound. An “ultrasonic” deterrent device emits “ultrasonic” sound bursts in a frequency of 25 kHz (25,000 Hz) which falls in a region of relatively low sensitivity canine hearing, well above the region of greatest sensitivity.
Air horns or aerosol horns are also often used to deter an aggressive dog. Air horns produce sound bursts in the “audible” frequency range, and operate on a different principle from electromechanical horns. The air horn produces sound by discharging a gas at high velocity from a gas canister through a small orifice near the base of the horn. The gas jet contains broadband energy (i.e., at many acoustical frequencies). A flexible membrane, which traps a small volume of air, acts as a resonator or reed that concentrates the energy at the “natural” frequency of its lowest vibration mode.
As an example, Falcon Safety Products Inc., of Branchburg, N.J., produces a line of air horns having “audible” frequency ranges of from about 70 to 700 Hz, at 112 dB to 120 dB (SPL) at 10 feet.
As discussed above, the more distant a receiver of the sound (the dog) is from the sound source, the lower the perceived sound level (dB). For example, the perceived sound level (dB) of an “audible” air horn device which has a decibel level of 112 dB to 120 dB (SPL) at 10 feet (approximately equal to 3.048 meters) would be greater at a distance of 1 meter. However, the sound pressure level (dB) is only one component of the sound. “Audible” sound blasts emitted by an air horn deterrent device in the frequency range of 70 Hz to 700 Hz also fall into a region of relatively low sensitivity canine hearing, below the region of greatest sensitivity.
Another major problem with many air horns is that the pressure of the gas and thus the sound output is inversely proportional to the temperature of the gas. Thus, on hot days, the pressure of the gas passing through the small orifice would be greater and could even freeze or cause ice to build up at the orifice as the gas expands through the orifice; and on very cold days, the pressure of the gas passing through the small orifice would be significantly reduced and may not produce any sound at all.
There are several patents that disclose electronic sound devices designed to disperse or deter various animals.
Evans, U.S. Pat. No. 3,058,103, discloses a device for chasing pests such as rodents and bugs including flies and mosquitoes. The device generates an ultrasonic alternating signal having a frequency in a range having the lower limit of the range above that discernible by a human being and having the upper limit of the range lying between 20 kHz and 35 kHz. The generated alternating signal is then preferably constantly varied between these limits. The generated signal is then amplified sufficiently to drive a transducer or speaker to produce a sound which is inaudible to the human ear (above 20 kHz). The speaker may also be alternately turned on and off in combination with the varying of the frequency referred to which rodents are incapable of withstanding, and as a result, they leave the area. In the case of bugs, such as flies and mosquitoes, the frequency is preferably varied in a range which extends from the upper range (20 Hz-35 kHz) to an upper range lying in the order of 200 kHz.
Stewart, U.S. Pat. No. 3,683,113, discloses a synthetic animal sound generator and method for ridding an area of pest birds by generating signals that correspond to warning or alarm signals normally created by the birds themselves. The apparatus generates a carrier signal in a frequency range of about 500 Hz to about 5,000 Hz. The carrier signal is modulated by a lower frequency AC signal in the range of about 50 to 300 Hz to form a composite signal which is intermittently silenced to generate a plurality of signal pulses. The modulated carrier signal is intermittently interrupted at a rate of at least about once per second to produce a chirping sound, and an electro-acoustic transducer converts the modulated and intermittently interrupted carrier signal to a sound signal which is directed at the pest birds.
Beuter et al, U.S. Pat. No. 4,769,794, discloses a bird-scaring method and device wherein at least two acoustic signals are generated whose frequencies are periodically modulated within a range between about 30 Hz and 9,000 Hz, the modulation period ranging between about 0.01 and about 5 seconds. The signals differ in the frequency modulation range, in the modulation period and/or in duration, and may be emitted either in fixed or in arbitrary sequence. The interval between the individual signals can be between 20 seconds and 1 hour, preferably between 1 and 30 minutes, in particular between 5 and 20 minutes. Each of the signals are frequency-modulated preferably between 100 Hz and 7,000 Hz, in particular between 150 Hz and 5,000 Hz. The modulation period ranges between about 0.01 and 5 seconds, preferably between 0.02 and 2 seconds, in particular between 0.05 and 1 second. Particularly favorable results are obtained if the range in which frequency modulation occurs covers at least 2,000 Hz. The lower limit of the frequency modulation range should preferably be, however, between 1,000 Hz and 100 Hz, in particular between 500 Hz and 100 Hz. The duration of each individual signal is between 1 and 30 seconds, preferably between 10 and 20 seconds. Due to the measure according to the invention, a sound pressure level of about 60 dB at the place of sound emission is sufficient.
Carlo et al, U.S. Pat. No. 5,278,537, discloses an electronic vehicle mounted alarm for avoiding collision with animals in a non-destructive manner, which generates ultrasonic sound for preventing animals from moving into the path of the vehicle. The device generates electrical impulses in the form of square waves having constant peak-to-peak voltages with periodic, sequentially increasing wave frequencies followed by sequentially decreasing wave frequencies. A coupling transformer converts the square waves into electrical sine wave voltages having high peak-to-peak voltages to cause a piezo-electric transducer to emit intense, ultrasonic sounds of periodically increasing frequencies in a range from 19 kHz to 30 kHz (19,000 Hz to 30,000 Hz) followed by periodically decreasing frequencies simulating the warble effect of a siren. A preferred frequency pattern commences at 21 kHz (21,000 Hz) and continues until 24 kHz (24,000 Hz) immediately followed by a decrease in sequence from 24 kHz to 21 kHz. The ultrasonic warble effect confuses the animal to prevent inadvertent movement by the animal into the oncoming vehicle's path without injury to the animal.
Canfield, U.S. Pat. No. 6,677,853, discloses an animal deterrent system using the vehicle horn to deter auto collisions with animals, and more specifically to allow the standard automobile horn to be altered in a manner such that the noise alerts animals, particularly deer, to the presence of an approaching vehicle. A timer/oscillator is selectively connected between the vehicle horn actuator (e.g., the button on the steering wheel of the vehicle) and the vehicle horn. When the timer is connected between the horn actuator and the horn, a continuous input to the horn actuator is converted to an intermittent horn output (preferably cycling between 2 Hz and 20 Hz), with the intermittent horn output synchronized with the timer pulses.
Ewert et al, U.S. Pat. No. 7,042,340, discloses a vehicle mounted animal alerting device that produces a sound that stimulates an alertness response in large animals, such as a deer, to reduce the likelihood that the animals will run into a roadway and cause an animal-vehicle crash. The sound produced by the device is a random intermittent sound pattern in an audible frequency range (in the same general range that humans can hear). More specifically, an animal alerting device in accord with a preferred Ewert et al embodiment produces sounds generally in the range of 1-10 kHz (1,000 to 10,000 Hz) and, more specifically, in the range of 1-5 kHz (1,000 to 5,000 Hz). The volume of the sound produced is automatically adjusted for vehicle speed. For example, in a vehicle traveling at highway speed the sound is amplified to a relatively high level, e.g., approximately 80 dB or more. Different sound patterns may be produced automatically based on different geographical locations of the vehicle in which the device is mounted.
Perlo et al, U.S. Pat. No. 7,098,775, discloses a system and method for avoiding the collision of a vehicle with animals tending to cross the road before the moving vehicle. The system comprises a visual system directly actuating one or more RF emitters, emitting directional ultrasonic sound waves with a frequency above 25,000 Hz (25 kHz), the range above that discernible by a human being. The sound waves are directed frontally though with a frequency decreasing from the center of the roadway towards the road edge, so as to lead the animal to move towards the road edge.
There are also several patents that disclose electronic sound devices designed to train animals, such as canines. For example, Duncan et al, U.S. Pat. No. 6,750,758, discloses a collar-mounted remotely controlled beeper training device which includes a piezoelectric transducer device mounted in a transducer housing configured as a resonant sound port. The piezoelectric transducer is driven by circuitry including a microcontroller, a voltage booster circuit, and driver circuitry coupled to the booster circuit producing a boosted drive signal to the piezoelectric device. The microcontroller stores data representing a plurality of sequential segments each having a start and stop time and a start and stop frequency representative of an animal sound, such as a hawk scream, and a program executed by the microcontroller sequentially produces a plurality of output signals having a start and stop times and frequencies in response to the stored data so as to accurately reproduce the animal sounds.
There are also several patents that disclose electronic sound devices designed to “attract” animals, rather than disperse or deter them, and other uses.
Solow, U.S. Published Patent Applications 2008/0258883 (abandoned) and 2008/0084282 (now U.S. Pat. No. 8,004,390) disclose a an electro-mechanical horn device having a body, a sound-generating unit mounted in the body, and plural compartments for storing at least one removably mounted battery and a second battery in an operative manner thereby enabling enhanced battery storage and limiting discontinuity of the operation of the sound-generating unit. The sound-generating unit includes an oscillator that provides a series of pulses to an electromagnet speaker having a coil electromagnet and diaphragm. A CPU controller containing pre-recorded digital sounds reproduces previously recorded signals, such as animal sounds, warning signals, etc. The frequency of the sound may be selectively adjusted to generate the sound of a chosen animal. For example, sound signals at a frequency and pitch generally similar to those made by a wild turkey, so as to attract another turkey. The pitch of the horn is determined by the flexibility of the diaphragm; its physical size; the power of the electromagnet; the mass of the diaphragm, and a number of other contributing factors. The pulses have a repetition rate substantially less than the natural frequency (3,000 Hz) of the diaphragm. The horn may be used for sports activity (hunting), sporting events, and emergency rescue operations.